Jeanie, "insider knowledge" BEFORE(!) the Prep....Herington House rings no bells, but a formidable lady known as Miss Duggan who ran "Arnold House" in Brentwood (up the hill, towards Warley) could be a different matter, assuming my memory is correct. There's almost enough info here for an edition of "This is your Life"!!
       I will pass on your good wishes to Nic & Julia,
                                          Very Best,
                                                   Nigel P.